Question

$\begin{array}{cc}\text{Column - I}& \text{Column - II}\\ \text{(a) 3,3,4,4-tetramethyl-1-pentyne}& \text{(p) Has only three collinear carbons}\\ \text{(b) 2-butyne}& \text{(q) Has four collinear carbons}\\ \text{(c) 1-butyne}& \text{(r) Substitution of H by Cl gives single product}\\ \text{(d) 2,2,5,5-tetramethyl-3-hexyne}& \text{(s) Substitution of H by Cl gives three different}\\ & \text{product (excluding stereoisomers)}\end{array}$

• A. $a\to p,s;b\to q,r;c\to p,s;d\to q,r$
• B. $a\to p,r;b\to q,r;c\to p,s;d\to q,s$
• C. $a\to q,s;b\to p,r;c\to s;d\to q,r$
• D. $a\to q,s;b\to q,r;c\to p,s;d\to q,r$

Answer 1

The correct option is A $a\to p,s;b\to q,r;c\to p,s;d\to q,r$

(a)Carbon 1, 2 and 3 are collinear
Also it has only three (underlined) non-equivalent hydrogens, gives three chloro alkynes in substitution reaction.

(b) All four carbons are collinear
Also it has six hydrogens equivalent, hence only one product is formed after the hydrogen is substituted by chlorine.

(c) Only three carbons are collinear
Also it has three non-equilavent hydrogens, hence gives three different products after substitution of H by Cl.

(d) The sp-hybridised carbon and two $\alpha -$carbons bonded to sp carbons are collinear.
Also all its hydrogen atoms are equivalent, gives only one chlorinated product on sustitution of H by Cl